For that kind of current levels, a 74HC-based device offers far more flexibility.

 

@dannyf

Thanks, after work I'll try to build and understand why that circuit works. I'm sure it's easy too after I have some time to understand where the current wants to go.

Just quickly though, does that circuit continually turn the trigger on and off depending on the output?

Also, thanks for the example so I can build it and see it.

 

@GopherT

The MrChips solution created the inversion I wanted, and I could see how to attach the components with the schematic. I currently don't understand how the diode option would work, or where exactly to put it to create the inversion I need. I can try to google 555 timer with diode later, if I find some examples I'll try it out on my breadboard.

@dannyf @ErnieM

"the simplest solution there would have been to put the led between the output pin and the rail. no other device needed at all."

I'm too much of a novice to see this one clearly. You are saying just putting the LED between the 5v rail and the 555 output without a resistor will invert the blinking? I can try it after work.

It does not make sense to me because on my circuit for ~7 seconds there is power coming out of the output pin #3, and then it's off for ~.5seconds. If I just put a LED... OH!

Ok that's cool!. It's still good to use a resistor in this method right? I mean I should be able to do this with any load not just a single LED right?

Haha, that just dawned on me. Damn it's so easy now, thanks for sticking with me, that must be about the most basic principle of electronics to have to try and explain. You made it so the only time there is a path to ground is when the 555 timer is in it's off position.

Stupid mental disconnects.

If I followed your stream of consciousness correctly then you have it. Both the led and resistor connect not from output to ground but from 9V to output.

Yes the 555 can either drive power out when it is on, and also sink current to ground when off. This is what a push-pull output stage does, and the 555 has one.

You now have several competing solutions mixed up in this thread. hope you see that. Your schematic in your post #13 has all the parts you need, you just have to move the LED and resistor around to change the flash.

And no need for an apology, helping people sort out their problems is what we like about this place. You are doing your share of the work and not asking us to do it for you.

 

I experimented with a particular 555 timer (NA555P from NXP). C1=47u, R1=100k, R2=0 (shorted out). At 5v/12v, it gives about 8 seconds on/off cycle. The led blinks on for less than half a second but with persistence of vision, it doesn't seem to matter that much.

 

You asked for a way to invert the 555-timer output. Hence the direct answer is to use an inverter.

If you had asked to invert the way an LED flashes from a 555-timer, i.e. short flashes instead of long flashes, then the answer is simple, drive the LED from the high side, i.e. the +V supply rail.

The 555-timer output can supply current as well as sink current. For your solution you want the 555 output to sink current.

Use the upper LED in the circuit shown above.

 

@MrChips

You are right, I wasn't clear enough. But I'm still happy you answered the question as asked because learning that parallel trick with the transistor will come in handy in the future.

 

No problem. It's always good to have various solutions to a problem.
That is what's good about AAC. Many eyes see things differently.

 

A nit, but a transistor used as a switch is Class D operation.
Class A is continuous operation in the linear mode.

I meant to carry the INVERTING aspect to the focus of my Class A comment. In the case of a Class A, the load (LED in this case) is connected to ground in parallel with the transistor to create the inverting output.

It seems to me that the load in a Class D is the collector resistor and, therefore, no inversion in the output.

 

I can't find a circuit like that, what do I ask google to find an example of a transistor changing the high and low?

I'm probably thinking about it wrong, but when I used a transistor before, sending positive to the base turned the NPN emitter and collector on.

you remember correctly. But when using an NPN transistor, you switch the low side. That is when the base is high, the collector is connected to ground, or low.

 

@djsfantasi
Welcome to 2020.
John

 

As an aside, for future reference, there is a class of logic called "single gate logic"
that packages simple gates and flops in small packages. Used by FPGA and ASIC
designers to fix missed or incorrect design flaws in circuits, as well as low end stuff
that only needs simple gate or two. Very small packages/pinouts available.

https://www.diodes.com/products/logic/single-gate/

https://toshiba.semicon-storage.com/us/product/logic/one-gate-logic.html

http://www.ti.com/lit/scyt129

https://www.onsemi.com/products/standard-logic/logic-gates


Regards, Dana.